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- Response models in experimental studies of fresh properties of cement pastes: Part I – typical approach through changes one-variable-at-a-timePublication . Maia, LinoThe experimental plan affects the fresh properties cement-based materials. This document regards to Part I of a major work wherein workability of cement-based pastes is evaluated. Here, several cement based paste compositions incorporating distinct constituent materials were tested and their effect on the measured. The overall work is composed by two parts. Here, in Part I, basic and typical run of experiments wherein only one input parameter is studied at once were applied. The results of Part I shown that basic run of experiments is easy and quick of develop and leads to results of easy analyses, however advanced and scientific analyses are difficult.
- Influence of supplementary cementitious materials on fresh properties of 3D printable materialsPublication . Teixeira, João; Schaefer, Cecília Ogliari; Maia, Lino; Rangel, Bárbara; Neto, Rui; Alves, Jorge LinoThe development of printers and materials for 3D Printing Construction during the last two decades has allowed the construction of increasingly complex projects. Some of them have broken construction speed records due to the simplification of the construction process, particularly in non-standard geometries. However, for performance and security reasons the materials used had considerable amounts of Portland cement (PC), a constituent that increases the cost and environmental impact of 3D Printable Materials (3DPM). Supplementary Cement Materials (SCM), such as fly ash, silica fume and metakaolin, have been considered a good solution to partially replace PC. This work aims to study the inclusion of limestone filler, fly ash and metakaolin as SCM in 3DPM. Firstly, a brief literature review was made to understand how these SCM can improve the materials’ 3DP capacity, and which methods are used to evaluate them. Based on the literature review, a laboratory methodology is proposed to assess 3DP properties, where tests such as slump and flow table are suggested. The influence of each SCM is evaluated by performing all tests on mortars with different dosages of each SCM. Finally, a mechanical extruder is used to extrude the developed mortars, which allowed us to compare the results of slump and flow table tests with the quality of extruded samples.
- Estudo Comparativo de Fundações para um Edifício Modelo em João Pessoa/PB: Sapata X Estaca Hélice ContínuaPublication . Ribeiro, Amanda Sílvia Sousa; Mendonça, Fernanda Calado; Maia, Lino Manuel SerraO objetivo deste estudo é verificar qual tipo de fundação é mais viável para um solo na cidade de João Pessoa. Para isso, foram adotadas cargas pré-dimensionadas do projeto genérico de um edifício comercial e a caracterização do solo foi obtida através de um ensaio SPT. Em posse desses dados, foi possível o dimensionamento de uma sapata retangular e de uma estaca hélice contínua. Foram encontradas as resistências admissíveis para o sistema fundação-solo, para um edifício com quatro e doze pavimentos. Assim, para a proposta do edifício de quatro pavimentos, a sapata se mostrou eficiente em transmitir as cargas para o solo. Já no edifício de doze pavimentos, recorreu-se a um bloco com três estacas do tipo hélice contínua para transmitir de forma satisfatória as cargas solicitantes às camadas resistentes do solo.
- BIM model to support O&M tasksPublication . Carvalho, Ana Thereza; Calejo, Rui; Santos, José; Maia, Lino: Technological evolution and BIM have changed the design development process in the construction industry. The operation and maintenance (O&M) phase requires building information throughout its service life, which was previously paper based, making it difficult to carry out maintenance activities. BIM assists in the management, storage, and digital sharing of information generated. However, only part of the information generated is required for the maintenance phase of the building. Although a subset of the IFC schema already exists to describe the data exchange between the BIM model and maintenance software, the data are generic and not well defined according to each the element source of maintenance (ESM). Therefore, through a literature review of existing studies on the use of BIM to support O&M processes, this paper aims to design an information flow to integrate maintenance information into the BIM model. The information is based on six main maintenance acts (inspection, cleaning, proactive measure, correction, replacement, and terms of use) and organized in an external sheet. The building will be divided into ESM according to its function in the building to facilitate the maintenance information flow between sheets and the BIM model.
- Comparison of response models from full, fractionated and small central composite design of experiments in cement-based mortarsPublication . Cangussu, Nara; Matos, Ana Mafalda; Maia, LinoExperimenters often do not have adequate time, resources or budget to carry out large number of experiments. DOE based in factorial designs are a powerful tool for designing and optimizing advanced cement-based materials, such as high performance self-compacting mortars, where many constituents raw-materials are employed (binder phase, granular materials, and admixtures) and several engineering as aesthetics requirements. The objective of this work was to compare response models from full, fractional, and small Central Composite Design of experiments applied to mortars properties.
- Environmental Analysis of the Incorporation of Sugarcane Bagasse in Medium Density Particleboard Panels through Life Cycle AssessmentPublication . Cangussu, Nara; Vieira, Maria Luiza C.; Maia, LinoThe growth of civil construction and agroindustry, resulting from population growth, caused an increase in the demand for non-renewable resources and for the exploitation of natural resources. Consequently, it caused a greater generation of waste, causing the current scenario to require alternatives for the reuse of these materials. Particleboard panels, for example, used in civil construction, can add value to waste or materials of low acceptance, such as thinning wood, mechanical wood processing waste or agro-industrial waste. Thus, this study proposed to analyse the life cycle of the sugarcane bagasse, considering the stages of extraction of materials and energy resources until their final disposal. This study aimed to compare impacts generated by the production of particleboards panels produced with wood from plantations (pine) and with the sugarcane bagasse. As a result, a better environmental performance was obtained from the panel composed of sugarcane bagasse, as it generated lower environmental impacts in all impact categories studied. The benefits range from the reduction in waste disposed of in landfills, which increase its useful life, the lower demand for reforestation, with steps that generate atmospheric emissions and degrade the soil.
- Experimental dataset from a central composite design to develop mortars with self-compacting properties and high early age strengthPublication . Maia, LinoThe concrete workability and the compressive strength are the principal properties of the fresh and hardened concrete, respectively. When self-compacting properties are required, scientific knowledge is important and appropriate models ap plied to achieve optimized compositions. Here, experimen tal data regarding to the mortars is presented. The dataset regards to a design of experiments carried out in mor tars with commercial materials through a central compos ite design with five independent variables: Waterv/Cementv, Superplasticyzerm/Powderv, Waterv/Powderv, Sandv/Mortarv, FineSandv/Sandv. In total 64 mortar composition were done: 25 factorial design consisting on 32 treatment combinations augmented by 10 axial runs plus 8 central runs, resulting in a central composite design with 50 mortar trial mix compo sition. Beside 14 extra mixes were done to allow comparing and validating results for the response models to be applied. Four dependent variables were measured: the D-flow and the t-funnel to measure the workability and the tensile strength and the compressive at the age of 24 h to assess the me chanical properties. Since the experiments were run based in a central composite design and extra mixes were prepared, response models can be applied to the dataset in order to find optimized mix compositions.
- Durability in alkaline-activated materials a review on the state of the artPublication . Ventura, Sebastião; Maia, LinoThe present work on durability in materials obtained by alkaline activation (AAM), in state-of-the-art review format, is structured as follows. (I) -The concept of alkali activated materials-composition-performance; (II) - The prediction of the useful life of AAM-methodologies and planning; (III) - The durability and properties of Engineering-mechanical tests-standards of specifications and tests (IV)-Degradation processes of Chemical Matrix-resistance to sulfates (SO4-²), acids (HCl), (H4²2SO4) (HNO3), (H3PO4), (HF), (H2CO3) and sea waters; (V) Degradation processes by mass transport - permeability, porosity, corrosion, carbonation, efflorescence and ice-thawed.
- Numerical modeling and optimization of self-compacting mortars: central composite design approach withPublication . Cangussu, Nara; Matos, Ana Mafalda; Maia, LinoThe current work developed Statistical models to reach high-performance self compacting cement-based mortars for structural purposes. A central composite design approach was employed to describe mortar fresh and hardened properties (mechanical strength) in function of key mortar mixture design parameters. The fitted models allow to model and predict flowability and viscosity properties and find a range where self-compacting behavior existed. Sand to mortar volume ratio exhibited the main effect on flowability and viscosity, with a positive effect, which is explained by decreases in paste volume. As expected, the water to cement volume ratio had the highest effect on both flexure and mechanical strength of mortars.
- Low durability of concrete elements due to steel corrosion – cases wherein the steel reinforcing bars acted as an internal clock bombPublication . Maia, Lino; Alves, SérgioConcrete elements are expected to resist any process of deterioration to remain its original form, quality and serviceability when exposed to its intended service environment. As the concrete deteriorates durability problems progressively develop leading to structural damage, which might put users in a potential danger. Concrete deterioration may be categorized into three categories of causes: physical, chemical, and mechanical, from which major durability issues come from steel corrosion as a result of combined effect of multi environmental factors. This work reports examples wherein the corrosion of the steel reinforcing bars severely affected the concrete element durability. Five examples wherein the steel reinforcing bars got prematurely corroded, acting as an internal clock bomb for concrete element durability, are reported. It is questioned if the steel reinforcing bars were structurally (un)necessary and if (in)appropriate construction practices were used. Alternative solutions for higher durability are proposed.